The Investigated glass system is xCuO-(50-X0)B2O3-30Na2O-2oZnO,where x=1,3,4,5,7and 10 mol.%. The investigated glass has been prepared by conventional melt Quenching technique. The optical measurements were measured by using JENWAY (6405UV/Visible) spectrophometer covering the wave length range from 190 to 11oo nm. From optical absorption spectrum the energy gap and band tail were measured for all glass samples by using truces equations.